That was perhaps the most useful analysis in the whole of Tragedy and Hope. An even more interesting book by Quigley is The Evolution of Civilizations which paints a coherent picture of the chaos which we see as history. It describes the processes through which civilizations have arisen, flourished and collapsed. There are about two dozens true civilizations in world history. And they go through the same processes.
That said, I don't share Quigley's elitist views and his contempt for the common man. At the end of the day, Quigley felt that humankind would be better off under the guidance of a ruling class elite. I think we've had quite enough of that.
Carroll Quigley postulated that Western civilizations proceed through the following stages:
1. Mixture - different societies come into contact and produce a society with an outlook different from any of the combined parts.
2. Gestation - the period of time between the mixing of the different societies and the expansion of the civilization.
3. Expansion - the surplus generated by the society is invested in activities that benefit the civilization. This can include an increase in knowledge, increase in physical area, technological advancements that increase efficiency, etc. Civilizations make use of different instruments of expansion. Quigley calls a social organization or unit an instrument if it meets social needs.
4. Age of Conflict - The rate of increase resulting from the use of one or more social instruments slows down which results in "interesting times". The instrument can be reformed or a new instrument consistent with the civilization's outlook can circumvent the old instrument. If reform is achieved, a new age of expansion begins. If the vested interests of the previous instrument of expansion increasingly consume resources while serving no social needs, Quigley says that the instrument has then become an institution. Expansion can continue, but it is at the expense of neighbors, which leads to imperialist wars. When the vested interests have crushed all internal opposition, the next stage appears.
5. Universal Empire - typically a state or political unit on the periphery of the civilization gains power over the whole civilization. The illusion of a golden age appears. The social organization remains stagnant.
6. Decay - lack of belief in the civilization's outlook or inability to meet needs of the people leads to people opting out of the system. An age of cynicism, low cunning and despair.
7. Invasion - external forces disrupt the civilization's social organization and it is unable or unwilling to defend itself. That spells the end of the civilization.
Quigley stated that modern Western civilization as embodied by America has succeeded in arriving at the brink of the Age of Conflict stage no fewer than four times, but has always managed to reinvigorate itself by launching into a new Age of Expansion. Recall that expansion in Quigley's terms doesn't necessarily apply to the acquisition of new territory. If he’s correct, we’re now out of options, and that we’ve progressed rapidly through to stage 6. As many of you know, I have my own ideas about what’s going on with respect to the role that the will to power has played in modern times.
An excellent reference work on civilizational collapse appears here: The Catastrophe” What the End of Bronze-Age Civilization Means for Modern Times